when is a PhD worth it?

To be interested in a PhD itself is a sign that you have specialized interests and skills that you would rather share with the world. Going through the process of attaining a PhD could be the onset of providing solutions that would make humanity better and safer. Otherwise, the PhD process could be so rigorous thus the only thread that would keep you connected is motivation.

A PhD can still be useful, but its value depends heavily on personal goals and professional aspirations. It is rewarding for those who truly enjoy research, discovery and the process of generating new knowledge, as well as for those who seek careers where a PhD is essential, such as academia. However, although academic research has become increasingly competitive, with limited permanent positions and dependence on project-based contracts, the research itself remains viable in many areas. For these reasons, the PhD should be regarded as useful both as a pathway to specialised skills and as an education that provides skills applicable outside academia. 

However, the common denominator in all of this is your motivation and passion for research, otherwise it is very difficult to approach such a path calmly.

In all cases Phd is worth however we have to put in our minds that studies are not only to earn money and there is a lot of skills top developp to sucess in professional life

Ph.D. is really worthen if you want to make your career in the research and academic point of view. Ph.D. work is essential for research and demonstration intensive industries. Ph.D. worth in the leadership roles in specialized sectors like government policy, and various NGOs for societal changes in the recent environments

Ph.D. is not worthen if you want to academics jobs and earn more money fast and explore more job options  

PhD is really worth when you register your work for IPR. Or when you implement your work in a society and industrial benefit. 90% of the PhDs are from academic background where very few only doing it for a purpose. Industries are not hiring any PhD candidates eventhough they are expert in that field. So nowadays PhD became one of the activity of research institution..and also demand of workplace.. Not creating any impact on society.